## Search found 31 matches

Sat Jun 09, 2018 8:28 pm
Forum: Bronsted Acids & Bases
Topic: 12.27
Replies: 1
Views: 215

### 12.27

Wants to prepare 200.0 mL of a 0.025 M HCl solution but uses a 250.0 mL flask
I understand part a but where does the equation pH = -log * (200mL * .025M)/250.0M come from for part b
Sat Jun 09, 2018 8:27 pm
Forum: Bronsted Acids & Bases
Topic: 12.15
Replies: 1
Views: 205

### 12.15

Calculate the initial molarity of Ba(OH)2 and the molarities of Ba2+, OH-, and H3O+ in an aqueous solution that contains 0.43h of Ba(OH)2 in 0.1L of solution. For this one I understand how to get the molares of Ba2+ and OH- by finding the number of mols of Ba(OH)2 then doing the math but I don’t und...
Sat Jun 09, 2018 8:24 pm
Forum: Bronsted Acids & Bases
Topic: 12.17
Replies: 1
Views: 193

### 12.17

State whether the following oxides are acids or bases or amphoteric.
For these, what is the best way to determine what they are by drawing the Lewis structure and then seeing if they want to gain or lose electrons?
Tue Jun 05, 2018 7:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 4.109
Replies: 1
Views: 99

### 4.109

Estimate the bond angles... when you are finding bond angles of an element with mutliple bonds how do you just find one of them?
Tue Jun 05, 2018 7:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 4.43
Replies: 1
Views: 116

### 4.43

Noting that the bond angle of an sp3 hybridized atom is 109.5 and that of an sp2 hybridized atom is 120, do you expect the bond angle between two hybrid orbitals to increase or descremase as the s character of the hybrids is increased? In this question what is meant by the “s character” because isn’...
Tue Jun 05, 2018 7:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 4.27
Replies: 2
Views: 126

### 4.27

When there are more than 2 elements in a molecule how do you determine whether they are polar or non polar?
Wed May 30, 2018 12:35 pm
Forum: Lewis Structures
Topic: Test 3 Q2
Replies: 1
Views: 141

### Test 3 Q2

This one asked for the most stable lewis structure of carbon monoxide and I drew it as C with two lone pair electrons double bonded to an O with four lone pair of electrons but the right answer is C with two lone pair electrons triple bonded to O with one lone pair electron. I am confused on this be...
Wed May 30, 2018 12:30 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: How to know what position lone pair electrons will be at?
Replies: 1
Views: 61

### Re: How to know what position lone pair electrons will be at?

I am pretty sure in molecules like this one of the lone pairs are going backwards (into the board) and one of the lone pairs are going forward (out of the board) and it is just hard to visualize when we are writing this on paper.
Sun May 20, 2018 10:29 pm
Forum: Bond Lengths & Energies
Topic: 3.87
Replies: 5
Views: 250

### 3.87

Which do you predict to have the stronger CX bond, where x is a halogen CF4, CCl4, CBr4
How do you judge the strength of the bond using length when they all are connected by only 4 single bonds?
Sun May 20, 2018 3:10 pm
Forum: Octet Exceptions
Topic: Expanded octects
Replies: 2
Views: 177

### Expanded octects

What are all the elements with expanded octects that we are expected to know?
Sun May 20, 2018 3:09 pm
Forum: Octet Exceptions
Topic: 3.59
Replies: 1
Views: 107

### 3.59

How is the Lewis structure for this one correct if neither of them have full octects and the formal charge is a 4?
Sun May 20, 2018 1:30 pm
Forum: Octet Exceptions
Topic: 3.55
Replies: 1
Views: 117

### 3.55

For this one the answers are
Which I understand but for
C) BF4- I get 32 electrons but it says that it is a radical
D) BRO I get 11 electrons and it says it’s NOT a radical so am I doing something wrong or why is this?
Sun May 20, 2018 12:22 pm
Forum: Octet Exceptions
Topic: 3.53 b
Replies: 1
Views: 104

### 3.53 b

For b (the second one) when you get O formal charge of -1 and S formal charge of 1 do those cancel out and equal a formal charge of 0? If so, why aren’t the two structures equal in energy?
Sun May 13, 2018 9:14 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron configuration
Replies: 7
Views: 282

### Re: Electron configuration

It doesn't matter as long as they are going in parallel with each other to fill all the orbitals, but conventionally they start with a (+1/2) or up arrow spin.
Sun May 13, 2018 10:01 am
Forum: Ionic & Covalent Bonds
Topic: 3.33
Replies: 5
Views: 186

### 3.33

For these, how do we know which letter should be in the middle? I know it is lowest ionization energy but what if two elements are in two different rows and groups? How can you tell?
Sun May 13, 2018 9:59 am
Forum: Ionic & Covalent Bonds
Topic: 3.25/ 3.27
Replies: 1
Views: 102

### 3.25/ 3.27

On the basis of the expected charges on the monatomic ions, give a chemical formula of each of the following ions?
Can someone please run through how to do these?
Sun May 06, 2018 10:00 pm
Forum: Trends in The Periodic Table
Topic: Unicorn practice test 6d.
Replies: 3
Views: 174

### Unicorn practice test 6d.

In the review session he explained that although ionization energies increase across a period when comparing C, N, O, F the order is C O N then F
I know he said that O is more inclined to lose an electron than N but why?
Sun May 06, 2018 7:55 pm
Forum: Trends in The Periodic Table
Topic: 2.71
Replies: 1
Views: 82

### 2.71

What is a diagonal relationship? I looked it up and it said similarity in chemical properties between an element in the periodic table ande one group lying one period lower and one group to the right.
I don’t remember him talking about this in class... do we need to know it for the midterm?
Sun May 06, 2018 7:53 pm
Forum: Trends in The Periodic Table
Topic: 2.67
Replies: 3
Views: 102

### 2.67

Which element of the following has a higher electron affinity?
So electron affinity means: amount of energy released when an electron is added to a neutral atom or molecule in the gaseous state to form a (-) ion.
Is this the same as ionization energy? What is the trend for this?
Sun Apr 29, 2018 8:38 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 2.25
Replies: 3
Views: 130

### 2.25

How many electrons can occupy the...
Is there an easier way to memorize/ understand how many orbitals each level has or do I just have to memorize the chart?
Sun Apr 29, 2018 8:28 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 2.21
Replies: 1
Views: 68

### 2.21

What are the principal and orbital angular momentum quantum numbers for each of the following orbitals?
for d) 5f, why does l = 3?
Sun Apr 29, 2018 8:23 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 2.13
Replies: 3
Views: 98

### 2.13

Describe the orientation of the lobes in the px, py, and pz orbitals with respect to the cartesian axis. The answers to this made sense because the lobes are orientated along the corresponding letters (px orbital will have its lobes orientated along the x axis) But what do these lobes refer to and w...
Fri Apr 20, 2018 12:59 pm
Forum: Photoelectric Effect
Topic: Wave properties of electrons
Replies: 2
Views: 103

### Wave properties of electrons

Can someone please explain to be the difference between constructive and destructive waves and what exactly it means?
Fri Apr 20, 2018 12:53 pm
Forum: Properties of Light
Topic: Wavelengths
Replies: 8
Views: 295

### Wavelengths

For the wavelengths spectrum do we need to know all the exact lengths for microwave, infrared, visible (red, orange, yellow, green, blue, violet), x- ray, y-ray or just the general idea?
Fri Apr 20, 2018 12:48 pm
Forum: Properties of Electrons
Topic: 1.57 [ENDORSED]
Replies: 2
Views: 156

### 1.57[ENDORSED]

Lines in the Balmer series of the hydrogen spectrum observed at 656.3, 486.1, 434.0 and 410.2 nm. What is the wave length of the next line in the series?
I understand that n1 is 2 because its the Balmer series but how do you get n2 is 7, shouldn’t it be 6?
Sun Apr 15, 2018 12:12 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Homework 1.13 [ENDORSED]
Replies: 3
Views: 167

### Re: Homework 1.13[ENDORSED]

Rydbery formula:
V=R(1/n1^2 + 1/n2^2)
C=vλ
So you can just substitute Rydbery formula for V since thats what it equals.
C=R(1/n1^2 + 1/n2^2)λ

Then just plug in your numbers
Sun Apr 15, 2018 12:08 pm
Forum: Properties of Light
Topic: 1.11
Replies: 2
Views: 129

### 1.11

What is common to the lines within a series that makes grouping them together logical?
Sun Apr 15, 2018 12:07 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Question 1.13
Replies: 1
Views: 79

### Question 1.13

Calculate the wavelength of radiation (using the Rydberg formula) generated by the transition from n=4 to n=2.

In the answer n1= 2 and n2= 4 but I don’t understand why it isn’t the other way around because its going from 4-2.
Sat Apr 07, 2018 9:20 am
Forum: Molarity, Solutions, Dilutions
Topic: Video 4 - post assessment [ENDORSED]
Replies: 2
Views: 137

### Video 4 - post assessment[ENDORSED]

A solution is prepared by dissolving 55.1 g of KCl in approximately 75 mL of water and then adding water to a final volume of 125 mL. What is the molarity of KCl in this solution?
Sat Apr 07, 2018 9:18 am
Forum: Limiting Reactant Calculations
Topic: Video 3 Post- assessment [ENDORSED]
Replies: 1
Views: 86

### Video 3 Post- assessment[ENDORSED]

PCl3 + 3H2O -> 3HCl + H3PO3. What mass is produced by the reaction of 23.6 g of PCl?
Sat Apr 07, 2018 9:16 am
Forum: Limiting Reactant Calculations
Topic: Video 3 Post- assessment
Replies: 1
Views: 89

### Video 3 Post- assessment

750 g of CHH9Cl13 is mixed with 1.0 kg of AgNO3 in a flask of water. AgCl precipitates out - what is the mass of AgCl.